<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
    下拉框：
    <select v-model="selected">
        <option value="disabled">--请选择--</option>
        <option>A</option>
        <option>B</option>
        <option>C</option>
    </select>
    <span>value:{{selectedd}}</span>

</div>

<!--导入Vue.js-->

<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>


<script>

    var vm = new Vue({
        el: "#app",
        data: {
            selected: ''
        }
    });

</script>
</body>
</html>